Catheter systems are well known in the art for use in medical procedures, such as diagnostic, therapeutic and ablative procedures. Typical catheter systems generally include an elongate flexible catheter shaft extending from a handle. A physician manipulates the catheter through the patient's vasculature to an intended site within the patient. The catheter typically carries one or more working components, such as electrodes and thermocouples, or other diagnostic, therapeutic or ablative devices for carrying out the procedures. One or more controls or actuators may be provided on the handle for selectively adjusting one or more characteristics of the working components.
Since the path through the patient's vasculature to the intended site is often long and tortuous, steering forces typically must be transmitted over relatively great distances. Accordingly, it is generally desirable for a catheter to have sufficient axial (e.g., column) strength to be pushed through the patient's vasculature via a force applied at its proximal end (“pushability”). It is also generally desirable for a catheter to transmit a torque applied at the proximal end to the distal end (“torqueability”). Pushability and torqueability (collectively, “maneuverability”) permit an operator, such as a physician, to manipulate a catheter to an intended site and then properly orient the catheter during an ablation procedure. It is also generally desirable for a catheter, and specifically the catheter tip, to have sufficient flexibility to substantially conform to the patient's vasculature and yet resist kinking as it does so. Kinking is often the result of a localized failure of the material of the catheter when localized stresses exceed the yield strength of the material.
To provide the desired pushability, torqueability, flexibility, and kink resistance, many catheter shafts are made at least partially of thermoplastic polymer materials that may be reinforced with a secondary material. The desirable characteristics of pushability, torqueability, flexibility, and kink resistance are often in tension or conflict with one another, however, with improvements in one requiring compromises in another.